1. Field of the Invention
The present invention relates to a film-forming method and a film-forming apparatus for forming a silicon oxide film on a tungsten film or a tungsten oxide film.
2. Description of the Related Art
When a semiconductor device is manufactured, a silicon oxide (SiO2) film may be formed on a tungsten film.
For example, a technology of forming a silicon oxide film on a metal such as tungsten is disclosed in Patent Reference 1.
However, when a silicon oxide film is formed on a tungsten (W) film or a tungsten oxide (WO3) film, since a rate at which silicon is adsorbed to a surface of tungsten or tungsten oxide is slow in initial film formation stage, an incubation time taken before the silicon oxide film begins to grow is long. Since the incubation time is long, a film thickness of the silicon oxide film formed on the tungsten film or the tungsten oxide film is less than that of a silicon oxide film formed on a base other than tungsten. Also, when silicon is not sufficiently adsorbed, for example, in the initial film formation stage, since tungsten is oxidized by contacting with an oxidizing agent directly, a tungsten oxide film is further formed.